1) Field of the Invention
The present invention relates generally to battery operated starting systems, and, more specifically, to circuitry for jump starting a vehicle having an electrical system of one voltage, typically twelve volts, with another vehicle having an electrical system with a system which may have a substantially higher voltage, such as twenty-four volts.
2) Related Art
Utility vehicles and similar consumer oriented products typically have a nominal twelve volt system for starting, running and accessory operation. If the battery discharges to a level below that necessary for starting, a jump starting procedure is employed using another vehicle or portable device to provide sufficient starting power to the disabled vehicle. In many situations, the assisting device has the same nominal voltage as the disabled vehicle so a direct battery-to-battery connection can be made simply. However, the starting device may have a substantially higher voltage than the disabled vehicle, such as is the situation when a vehicle with a twelve volt system is operated among military vehicles which usually have twenty-four volt systems. If the jumper cables between the twelve volt system and the twenty-four volt system remain connected too long, battery or vehicle component damage or wiring damage can occur. Disconnecting the cable too soon prevents the discharged battery from receiving enough charge for restarting the engine if for any reason there is a shut-down shortly after the jump start.
Some jump start systems have control devices associated directly with the cables or with the jump vehicle. Other systems include expensive DC to DC converters. Such devices add substantial cost and complexity to a system and, in operations such as the military where most all vehicles operate at twenty-four volts, equipping all jump start systems with protective circuitry or DC to DC converters that are only necessary with a relative few twelve-volt systems would not be practical or cost-effective.